Protein phosphorylation, for example at serine, threonine, and tyrosine residues, is a key regulatory mechanism for a variety of cellular processes. Protein phosphorylation is influenced primarily by enzymes of two types, namely protein kinases (PKs) and protein phosphatases (PPs). PKs catalyze addition of a phosphate moiety to a protein amino acid residue (generally a serine, threonine, or tyrosine residue), and PPs catalyze removal of such moieties. The catalytic activities of PKs and PPs are, in turn, influenced by the state of the cell and the environment in which it finds itself.
Myotonic dystrophy type PKs (MDPKs) are associated with modulation of cell morphology, shape, and contractility. MDPKs are also known to modulate the activity of skeletal muscle voltage-gated sodium channels, but not cardiac muscle voltage-gated sodium channels. MDPKs thus have a role in a variety of musculodegenerative and other musculoskeletal disorders including, for example, muscular dystrophy (MD) of various types (e.g., Duchenne's MD, limb-girdle MD, Becker MD, facioscapulohumerol MD, mitochondrial myopathy, and congenital myopathy) and myotonic dystrophies (e.g., Steinert's disease and Thomsen's disease).
Numerous MDPKs have been described, and many more are believed to exist. In view of the widespread and critical nature of MDPK activities in normal and pathological physiological processes, a need exists for identification of further members of this protein family. The present invention satisfies this need by providing a novel human MDPK.